The invention broadly relates to high pressure washing devices and is specifically directed to a portable pressure washer the entirety of which is hand-held (i.e., the entire device is carried and manipulated by the user during pressure washing functions).
High pressure washing devices exist in a wide variety of forms and perform many functions in industrial, commercial and home applications. These devices typically include an electric motor or gasoline internal combustion engine that drives a pump to which a high pressure spray wand is connected. Larger high pressure washers may be stationary and include a long hose that extends from a large electric motor and pump unit to the area of use, including a spray wand having a handle or trigger for controlling the spray. An example of a stationary high pressure washer is the type found in car washes.
More portable devices are available for home use, and although characterized as portable this generally means that the power/pump unit can be carried or wheeled from one place to another. A conventional garden hose is connected to the pump inlet, and a separate hose and spray wand is connected to the pump output. During use, the power/pump unit remains on the ground or other supporting surface, and flexibility of use results from the length of the output hose lending from the power/pump unit. The hose typically includes a spray wand that having a handle or trigger for turning the spray on or off. Such devices perform the high pressure spray function quite well, but are disadvantageous from the standpoint of size, weight and true portability.
The inventive portable pressure washer is the result of an endeavor to create a device that is fully portable in the sense of being hand-held. The inventive device is both small and light weight, and the entire unit is carried and manipulated by the user in performing the high pressure spray function.
In the preferred embodiment, the inventive portable pressure washer operates with a smaller, two-cycle internal combustion engine such as those used in chain saws, blowers and flexible line trimmers. The engine is carried in a housing having a primary handle which the user holds to both carry and to manipulate the device.
The pumping device is of the positive displacement type (e.g., vane-type), and the pump used in the preferred embodiment is specifically intended for use with electric motors rather than internal combustion engines and for entirely different applications. It has been adapted for the inventive pressure washer and is particularly advantageous for several reasons. First, it is relatively small and of relatively low weight, and hence particularly useful from the standpoint of full portability. Second, it operates in line with the internal combustion engine, thus lending itself to the concept of hand portability. Third, since it operates on a rotating vane principle, there is no pulsation in its output. Last, the vanes themselves are formed from a long wearing material such as carbon graphite, which means that the pump life is significant, and statistically longer than the engine life.
Matching this type of pump to a two-cycle engine is itself significant. As indicated above, the type of vane pump employed in the inventive device is normally intended for use with electric motors, which typically operate at a constant speed that is much lower than the operating speed of a two-cycle internal combustion engine. In the preferred embodiment, the vane pump is operated at approximately four times its normal speed. While this increased speed may lessen the anticipated pump life to a degree, the pump life is still much longer than the anticipated engine life.
The vane pump/engine match is also significant because conventional electric motors operate in a direction opposite that of internal combustion engines. While this would normally present a problem insofar that pump operation is concerned, vane pumps may be operated in either direction. The vane pump chosen for the inventive device can be easily modified for reverse operation by minor porting changes.
The engine and pump are coupled through a centrifugal clutch, which is also highly unusual for high pressure washing devices. Inclusion of the centrifugal clutch offers several distinct advantages, one of which is that coupling between the engine and pump is permitted only after the engine has reached a predetermined operational speed greater than idling speed. Second, and conversely, the pump only runs when the user wishes to generate a pressurized spray; i.e., by bringing the engine up to operating speed. Third, the engine and pump are uncoupled by the centrifugal clutch when the engine is at rest, enabling the engine ,to be started without the load of the pump. This not only makes the engine easier to start, but also requires less work on the part of the user during the start operation.
The spray wand of the inventive portable pressure washer is connected directly to the output of the pump. In the preferred embodiment, the wand is substantially rigid and is threaded directly into the output port, including a secondary handle enabling the user to carry and manipulate the device with both hands.
To operate the inventive portable pressure washer, all that is necessary is to connect a conventional hose to the pump inlet, open the hose faucet and to start the engine. The user thereafter raises or lowers engine speed as desired through the engine trigger, which starts and stops the pump through the intervention of the centrifugal clutch. With the pump running the user simply manipulates the device by pointing the wand and pressured spray head toward the object to be washed and brings the engine up to operating speed. As soon as the engine trigger is released, the engine falls to idling speed, the pump stops and the pressure spray ceases.